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Ghazi Khan
Ghazi Khan

Posted on • Originally published at

Mastering CSS Theming with CSS Variables

Originally posted on

In this blog post, we're diving deep into the realm of CSS theming using the power of CSS variables. By the end of this read, you'll grasp the intricacies of leveraging CSS variables to create dynamic and customizable themes for your web projects effortlessly.


Theming has always been a crucial aspect of web development, allowing us to tailor the visual appearance of our websites to suit different preferences and branding requirements. With the advent of CSS variables, the process of theming has become even more flexible and efficient.

Understanding CSS Variables

CSS variables, also known as custom properties, are entities defined by CSS authors that contain specific values to be reused throughout a document. They begin with two hyphens (--) followed by a name and can be used within any CSS property value.

Let's take a look at how CSS variables are declared:

:root {
  --primary-color: #007bff;
  --secondary-color: #6c757d;
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In this example, we've defined two CSS variables, --primary-color and --secondary-color, with their respective values.

Implementing CSS Theming

Now, let's delve into implementing CSS theming using CSS variables. Suppose we want to create a light and dark theme for our website.

/* Light Theme */
:root {
  --primary-color: #007bff;
  --background-color: #ffffff;
  --text-color: #333333;

/* Dark Theme */
.dark-theme {
  --primary-color: #61dafb;
  --background-color: #121212;
  --text-color: #ffffff;
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By defining different values for our CSS variables within separate themes, we can easily switch between themes by applying corresponding classes to our HTML elements.

Applying Theming to Elements

Now, let's apply our themed CSS variables to specific elements within our HTML markup.

<div class="container">
  <h1 style="--primary-color: var(--primary-color); color: var(--text-color);">
    Welcome to CSS Theming with CSS Variables
  <p style="--background-color: var(--background-color); color: var(--text-color);">
    Explore the power of dynamic theming in web development.
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In this example, we're using the var() function to reference our CSS variables within the style attribute of HTML elements, allowing us to dynamically apply our theme colors.


In conclusion, CSS variables provide a robust foundation for implementing dynamic theming in web development projects. By harnessing the power of CSS variables, you can create highly customizable and visually appealing themes with ease. Experiment with different color schemes and configurations to craft stunning user experiences that align with your project's requirements.

Start incorporating CSS theming with CSS variables into your projects today and unlock a world of creative possibilities!

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Top comments (2)

sinisterchef profile image
Kyle O'Brien

Thank you for the quick write up!

Since your code is using the :root pseudo class it would be beneficial to add a paragraph about the scope of defined variables. Essentially that :root acts as a global definition and all variables defined are only accessible to their children. Just a little note to help supplement your post.

gkhan205 profile image
Ghazi Khan

Thank you so much for your feedback and insightful suggestion! I truly appreciate your attention to detail.

Adding a paragraph about the scope of defined variables, particularly highlighting how the :root pseudo class functions as a global definition, is an excellent idea. It will definitely enhance the clarity and completeness of the post for readers. Your input is invaluable, and I'll make sure to incorporate this important information into the content. Thanks again for taking the time to share your thoughts! 😊🌟